I Promise That I'll Never Leave
by champagnealec
Summary: "As a final middle finger to the angels, for taking away her memories, Alec and Magnus get a very special wedding present, when they return to the loft after the reception." Malec. All Good Things... episode/coda fanfic. / First in the Infinity Rune series.


**Okay, I'm back after weeks of screaming over the episodes, with a 3x22 fanfic. My muse had one too many new ideas after these episodes came out and they're all demanding to be written out immediately.**

**And this is one of the many I have in mind to do, so be expecting a lot fanfics about these husbands!**

**Of course yes the title of the fanfic is from the wedding song "I Get to Love You" by Ruelle, because it destroyed me and the lyric here basically helped inspire this fanfic.  
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"Oh, shit!" Magnus exclaimed, breaking the much heated kiss with Alec, as he tripped on the rug right at the front door of their loft which caused him to tumble back some, he nearly fell to the ground and he probably would've, if Alec hadn't been quick and caught him with his shadowhunter reflexes, and so now they were chest to chest now and Alec's hands were rested on his back and waist.

Alec laughed lightly, placing a peck onto his lips, his face is flushed from their kissing that had began outside in the hallway, and his eyes are shining with pure love that he holds for him. "Are you okay, my husband?"

Magnus felt his breath catch at hearing the word _husband_ come from Alec's lips. He really still can't believe they actually married, really he can't. "I'm fine, thanks to you, Alexander."

Alec smiled and kissed his lips softly. "I always promised to catch you, when you fall, remember?"

"Hmmm, of course I do, my husband, and honestly you should, because you are the reason why I almost fell over," he stated, with a teasing smile, Alec just raised his eyebrows, he's sure that Alec knows he's teasing him, but doesn't say anything but his smile is slowly trying to become a smirk. "Well, if you hadn't jumped me the minute we got out of the portal, and waited until we were inside our loft and near the bedroom, then maybe I wouldn't have almost fell over," Magnus answered, and Alec is full on smirking now at him.

"You know how much I like you in a damn tuxedo, I just couldn't resist it anymore, and besides you weren't minding it too much, I might add." Alec pointed out, his hand trailing up from Magnus' waist to the lapel of his tux, gripping onto it tightly.

"Hmm, oh well, you caught me there, Alexander."

"Yes I did," Alec chuckled . "And now enough with the teasing, can I please take you to our bedroom, so I can make love to you?" He's already half leaning in, ready to connect their lips once more, Magnus rolled his eyes but nodded his head, and their lips meet once again, he lets himself be more carefully guided further into the loft by Alec who, kicked the front door shut as they moved more into the loft, and he laughed into their kiss, snapping his fingers, locking the door instantly because with their luck, a random person will interrupt them.

The kisses were filled with nothing but the love and happiness they felt and had at moment, they were just pouring all of it into the kisses, finally entering their bedroom, hands are tugging on jackets, they come to a stop in the middle of their room, all they do is just smile into their kissing, both are really just so fucking happy right now, they can't contain it.

Alec ends up breaking the kiss and cups Magnus' face with both of his hands, taking in all of Magnus' beauty. "God, I love you, I love you so much."

Magnus sighed contently, bringing his hand up to the back of Alec's neck and caresses his hair. "And I love you too, Alexander, so very much."

Alec beamed more brightly then before, and goes to pull Magnus back in for another kiss, when his eyes catch something that's laying on one of the pillows and he stopped mid-way and stares at the bed, his feelings changing from happy to confused in mere seconds. And Magnus who had his eyes closed, waiting for the kiss, opens them when he felt Alec stop himself mid way and sees that Alec is staring at their bed. He felt a little worried and confused as to why Alec was staring at their bed. "Alexander, what is it, dear?"

And he doesn't answer Magnus, instead Alec drops his hands from him and Magnus decides to see what the hell it was on their bed and turned his head to their bed, and he gets the answer. There laying on Alec's pillow on his side of the bed is an envelope with something written on the top of it but can't make out what is said and he could also see that the edges are burnt which means it got here by fire message but by who? And on today of all days, their wedding day, the only people who knew they were getting married was the ones he sent fire message invites to, the rest of the shadow world wouldn't find out until tomorrow about the wedding. "Who in the world sent a fire message?"

"I don't know, babe," Alec answered, moving away from Magnus and over to the bed, to grab the letter, Magnus watched him pick up the letter and looked closely at handwriting on the front, before he speaks. "It's Clary's handwriting," biscuit had sent the letter? That's odd. "Why would she sent us the letter, instead of giving it to us?"

"Maybe she didn't want to bother us, while we were having a great time at the reception," Magnus stated, walking over to where Alec was standing, holding the letter.

"Well, that is possible, since we were having fun, and it's our day," Alec said, giving his husband a smile before turning the attention back onto the letter. "I guess it's time to find out what the letter is about."

Magnus sits down on the side of their bed and Alec follows right behind him, they sat very close to each other, as Alec carefully ripped the envelope and takes out the letter, opening it up, and he and Magnus slowly read over what Clary had written to them.

'_Dear Alec and Magnus, I'm sure you are surprised to see a letter from me at your loft, it's better this way I didn't want to interrupt the happiest day of your lives, with everything that's happening, I explained that in another letter, but that's for you to know later on, I wanted to focus on the both of you right now, the happy couple. I've seen first hand how much you two have changed since you met each other and honestly it's a beautiful thing, you two are perfect for each other. And I've also seen first hand how many times you two have almost lost each other, I can't bare the thought of in the future that it might happen, even though I'm very sure Alec would've come up with something to keep from being away from you. I wanted to do this for you, I know you said no wedding gifts but I had to do this. _

_As a present to you both, I decided to use my gift and create a rune, (that you see at the bottom of the letter), a rune just for you two to use, nobody else. I'd like to call this rune the Infinity rune, because it is the symbol of it, but it also is like the Alliance rune I had drawn but very much different, while the Alliance rune was only a temporarily rune, that binds Downworlders and Shadowhunters together, the Infinity rune will bind you is permanently, yes, I said permanently and since it's just like the Alliance rune, Alec, Magnus this means you will share your abilities, which also includes Magnus' immortality. As long as Magnus is immortal and will live, so will you Alec. _

_You both deserve to be happy, that's why I did this, like I have said you have been through so much, you deserve this, unending happiness. And don't worry about anything bad coming from the runes being used, that falls on me, they can't do anything to you two. _

_I hope, you two use the rune and live a long and happy life together, changing the Shadow world, because I know you are destined to do that._

_Love, Clary.'_

The letter falls from Alec's hands as they finished it, it lands perfectly on the floor by Alec's feet, both are in shock and disbelief by what they just read from the letter, Magnus couldn't believe it, a rune that allows them to be bound together, share powers and his immortality, permanently. As long as he would live so would Alec and vice versa, it shouldn't be possible and yet it was. Clary made it happen, because she wanted to see them happy, and Magnus felt like he should be, but yet, at the same time there was thoughts in his head that told him, that Alec might not want this rune and if he did, he might just end up regretting it.

For a while there, him and Alec sit in silence, not saying anything, letting the information sink in, before Alec spoke up. "I can become immortal." And the emotions in Alec's voice, Magnus heard them, his hopes rise and his heart leaped. But he has to push them back because he might be reading it wrong.

"Alexander, I-" Magnus began to say, but Alec cuts him off by turning to face him and grabbed both of his hands, and holds them in his own, like he had done at their wedding just a few hours earlier.

"Magnus, I know what you are going to say, 'we can get rid of the letter, I know it's not what you want'. But in reality Magnus, it's all I want," Alec said, truthfully. Magnus felt like his breathing completely stopped then, and some tears well up in his eyes, did he just? Is he? "Remember what I said Magnus when I found you in Edom, I'm never leaving you again, I promised you that I'd never leave and I want to keep that promise to you, with this rune, Magnus, it can help me keep it."

He wants to become immortal with you, he means it, he never wants to leave you, apart of him says, but still some part of Magnus couldn't believe it and he has to make sure, he knows Alec is the type that overthinks a lot of things, through and throughout, but he has to make sure it's what he really wants. "Alexander, are you really, really sure this is what you want? The immortal life? It's long, hard, painful, losing the people you care about, I don't want you to regret it, because it's going to hurt, like hell."

"Magnus," Alec began, letting go one of his hands, to cup his face. "I want this, I really do, I know losing love ones will hurt, but I'm a shadowhunter, I made peace with the fact my siblings could die at any moment, in our line of work, it will hurt but I made peace with it, and you're forgetting you're my family too, long before you became my husband, like I said I'm not leaving you behind, never. So yes I want this Magnus, I want to be immortal with you."

Magnus felt overwhelmed with all of the emotions from hearing this, and only managed to whisper, "Alexander," before he kissed him, it's short, but very loving, when they part ways, Magnus kept his forehead rested against Alec's, staring at Alec's closed eyes. Alec really does want this and it's hard to believe it, because he's so used to being left behind and having Alec who doesn't want to do that to him, but here it is, Alec never wants to leave him, never.

"And I know it's a huge, huge step," Alec said, opening his eyes again to look at Magnus and pulling his head back just a tad. "And we most likely need to talk about it more, and we don't have to use the rune tonight, it's our wedding night after all, but I truly want this Magnus, I do, I really do."

"Alexander, while you're right about there needing to be more discussion on this, but I can see it in your eyes now, you really want this, so we will do it," Magnus told him, a smile begins to tug at Alec's lips. "But I agree, not tonight though, we have some time it's our wedding night and we have a honeymoon to go on.."

Alec nodded his head, his thumb caressing Magnus' cheek. "So we're really gonna do this, we are going to use the rune, bind ourselves together, share powers and immortality?"

"It appears so, my loving husband, but although we were already bound together, without a rune," Magnus pointed out, and Alec smiled so big and brightly.

"Well, that's true, babe." Alec agreed, giving Magnus a look that held adoration, and bumped his forehead gently against Magnus', "I love you, Magnus.."

Magnus returned Alec's look with one of his own. "I love you too, Alexander.." they grinned softly at each other, before leaning in to kiss once again.

After hundreds of years, nobody was ever willing to stay with him, forever, not a single person. Not until Alec, just now, it's only ever been Alec. Only him.

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**And once again the whole fanfic was written/edited like three days, another new record huh? I wasn't sure about it at first, but rereading it I like how it turned out, like I said before I like pushing myself to write these type of fanfics.**

**As for what's next, it's most likely another episode fanfic, probably for 3x21, because I like writing episode/missing scene fanfics.**

**Anyways, y'all know my tumblr: immortals-malec, where you can find my ass screaming over the Malec wedding currently.**

**Let me know what y'all thought and until next time.**

**~champagnealec **


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